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Deadly Fungus May Be Infecting Snakes Worldwide

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Closeup of the head of a milk snake, highlighting deterioriating scales on its nose and mouth.
A milk snake (Lampropeltis triangulum) showing signs of fungal and bacterial infections. 
© USGS National Wildlife Health Center/D.E. Green

A new study warns that a potentially deadly disease caused by the fungus Ophidiomyces ophidiodiicola, which already affects several species of snakes in the United States, can strike snake populations across the globe.

“This really is the worst-case scenario,” said Frank Burbrink, associate curator in the Museum’s Department of Herpetology  and lead author on the paper. “Our study suggests that first responders shouldn’t just be looking for certain types of snakes that have this disease, but at the whole community.”

The disease, known as snake fungal disease, has been found in 23 wild species in the United States, including ratsnakes, milksnakes, gartersnakes, and viperids, as well as in three European species. It causes fast-spreading lesions on the head and body. Though it can dissipate after the animal molts, rapid shedding and other changes to the animal’s daily habit in response to the infection—such as increased basking—can put snakes at a risk for other dangers, including predation, exposure, and starvation.


Closeup of the head of an eastern racer snake, highlighting the opaque eye and scale abnormalities.
An eastern racer (Coluber constrictor) showing signs of fungal skin infection. Obvious external abnormalities are an opaque infected eye, roughened crusty scales on the chin, and several discolored roughened scales on the side of neck. 
© USGS National Wildlife Health Center/D.E. Green

Researchers used an artificial neural network to search for potential common traits between snakes already infected by the disease and those that might be susceptible in the future. The results, published today in the journal Science Advances, showed that snakes infected with the disease shared no notable evolutionary, physical, or ecological traits—indicating that all snakes may be vulnerable.

“Some of the most devastating wildlife diseases ever documented, such as white-nose syndrome in bats and chytridiomycosis in amphibians, are caused by fungal pathogens,” said study co-author Jeffrey Lorch, a microbiologist with the U.S. Geological Survey National Wildlife Health Center. “These diseases have had such great impacts because they affect multiple species, and it now looks like the same is true of snake fungal disease.”


Northern water snake covered in raised blisters from nose to tail.
A northern water snake (Nerodia sipedon) with crusty and thickened scales overlaying raised blisters as a result of a fungal skin infection.
© USGS National Wildlife Health Center/D.E. Green

“Scientists have learned a lot about research and monitoring needs from 25 years of studying the effects of chytrid fungi on amphibians, and those lessons tell us that prevention is the best policy,” said Karen Lips, an associate professor of biology at the University of Maryland, College Park, and a co-author on the study. “Researchers need to work with decision makers to prevent snake fungal disease from spreading, survey museums and field sites to determine the current distribution of the disease, run trials in the lab, and start working on treatments.”